Colon as Target for Drug Delivery

Drug delivery through mouth is still the most acceptable route to administer bioactives for the patient. The colon targeted drug delivery has gained increasing attention towards the treatment of colorectal cancer and other colon related disorders i.e., Crohn's disease, ulcerative colitis, irritable bowel syndrome, and spastic colon. The drugs such as cardiovascular and antiasthmatic agents have also been delivered via colon to avoid first pass metabolism or acidic environment of stomach. Colon targeting has also been demonstrated as a potential tool for systemic delivery of protein/peptide drugs due to relatively low proteolytic activities in the colonic environment. The GIT is dwelt by over 500 bacterial species, each having a specific place in the tract and developing variety of enzymes which are being utilized for development of colon-targeted drug delivery systems. There are various strategies presently followed for colontargeted delivery i.e., prodrugs that become active at the colonic site, drug-eluting system reacting to the pH, microfloraactivated drug delivery systems, hydrogels and matrices, and multicoating time-dependent drug delivery systems. The future steering towards colon targeted bioactives delivery would involve the application of specific binding with colonic mucosa.